The importance of the Territories for biodiversity and
geodiversity

Globally threatened species

Of globally threatened species identified in the 2004 IUCN Red List, 74
critically endangered species occur in the UK Overseas Territories
(compared to 10 in mainland UK) along with 49 endangered species
(12 in mainland UK) and 117 vulnerable species (37 in the
mainland UK). Many of these species are endemic and so are found nowhere
else in the world. In addition, and as an indication of the
threat to island biodiversity, there are 39 recorded extinctions in
the UK Overseas Territories and two species are extinct in the
wild, compared with only a single extinction from the metropolitan
UK (namely the great auk). The latest extinction in the
Overseas Territories, the St Helena olive Nesiota
elliptica, occurred in 2003 when the last tree in cultivation
died (the last wild individual died in 1994). It is likely
that these figures are under-estimates; new studies invariably
report the occurrence of additional species or populations,
especially amongst the less well known taxa, such as
invertebrates.

Globally/regionally important concentrations of species

In
addition to numbers of globally threatened species, the Overseas
Territories also hold regionally or globally important
concentrations or assemblages of species. For example,
Ascension Island supports the second largest green turtle rookery
in the Atlantic; Gough Island (Tristan da Cunha) has been described
as, arguably, the most important seabird island in the world; and
the reefs of the Chagos Archipelago (British Indian Ocean
Territory) are some of the most pristine and best protected in
the Indian Ocean (and account for some 1.3% of the world
resource). The importance to nature conservation of parts of
the Territories is recognised through the designation of Gough
Island & Inaccessible Islands (Tristan) and Henderson Island
(Pitcairn) as World Heritage Sites for their insular natural
heritage interests.

Crown Dependencies

The Crown Dependencies have greater biogeographical
similarities with the mainland UK but are
notable, for:

a range of species found in the Channel Islands whose range
does not extend to mainland Britain;

insular forms of some species (such as the Guernsey vole);

populations of breeding birds (e.g. seabirds, chough and
hen harrier on the Isle of Man);

and for a range of marine and terrestrial habitats which are
significant in a UK and regional context.

Geomorphological features

There
has been no overall review of the importance of the Territories to
geodiversity but they contain geological and geomorphological
features, such as active volcanoes, glaciers and coral reefs that
are almost certainly significant in a regional or global
context.

Threats to biodiversity

Threats to the biodiversity of the Territories include
non-native species, climate change and the impacts of development.
Threats also come from fisheries, and tourism. Various conservation
projects have been set up in the territories to attempt to start to
address some of these threats.